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Summary of the First High-Altitude, Supersonic Flight Dynamics Test for the Low-Density Supersonic Decelerator Project

NASA's Low-Density Supersonic Decelerator Project is developing and testing the next generation of supersonic aerodynamic decelerators for planetary entry. A key element of that development is the testing of full-scale articles in conditions relevant to their intended use, primarily the tenuous Mars atmosphere. To achieve this testing, the LDSD project developed a test architecture similar to that used by the Viking Project in the early 1970's for the qualification of their supersonic parachute. A large, helium filled scientific balloon is used to hoist a 4.7 m blunt body test vehicle to an altitude of approximately 32 kilometers. The test vehicle is released from the balloon, spun up for gyroscopic stability, and accelerated to over four times the speed of sound and an altitude of 50 kilometers using a large solid rocket motor. Once at those conditions, the vehicle is despun and the test period begins. The first flight of this architecture occurred on June 28th of 2014. Though primarily a shake out flight of the new test system, the flight was also able to achieve an early test of two of the LDSD technologies, a large 6 m diameter Supersonic Inflatable Aerodynamic Decelerator (SIAD) and a large, 30.5 m nominal diameter supersonic parachute. This paper summarizes this first flight.

Clark, Ian G.↗

Viking and Mars Rover exobiology

Other than Earth, Mars is the planet generating the greatest interest among those researching and contemplating the origin and distribution of life throughout the universe. The similarity of the early environments of Earth and Mars, and the biological evolution on early Earth provides the motivation to seriously consider the possibility of a primordial Martian biosphere. In 1975 the Viking project launched two unmanned spacecraft to Mars with the intent of finding evidence of the existence of present or past life on this planet. Three Viking Biology experiments were employed: the Labeled Release experiment, the Gas Exchange Experiment, and the Pyrolytic Release experiment. Each of these three experiments tested for microbial existence and utilization of a substrate by examining the gases evolved from specific chemical reactions. Although the results of these experiments were inconclusive, they inferred that there are no traces of extant life on Mars. However, the experiments did not specifically look for indication of extinct life. Therefore, most of the exobiologic strategies and experiments suggested for the Mars Rover Sample Return Mission involve searching for signature of extinct life. The most significant biological signatures and chemical traces to detect include: isotopic and chemical signatures of metabolic activity, anomalous concentrations of certain metals, trace and microfossils, organically preserved materials, carbonates, nitrates, and evaporites.

Schwartz, D. E.↗

A Viking satellite orbit trim strategy

One strategy is submitted for meeting the varied and stringent requirements of the Viking Project on the control of the satellite orbit to obtain reconnaissance and to prepare for lander release. To satisfy these requirements, different orbit trim maneuver strategies were developed for two typical Viking missions. In addition, a summary of recent numerical results is included to show that this strategy satisfies the mission requirements which have been identified.

Hintz, G. R.↗

NORSTAR Project: Norfolk public schools student team for acoustical research

Development of the NORSTAR (Norfolk Public Student Team for Acoustical Research) Project includes the definition, design, fabrication, testing, analysis, and publishing the results of an acoustical experiment. The student-run program is based on a space flight organization similar to the Viking Project. The experiment will measure the scattering transfer of momentum from a sound field to spheres in a liquid medium. It is hoped that the experimental results will shed light on a difficult physics problem - the difference in scattering cross section (the overall effect of the sound wave scattering) for solid spheres and hollow spheres of differing wall thicknesses.

Fortunato, Ronald C.↗

The development of sine vibration test requirements for Viking lander capsule components

In connection with the Viking project for exploring the planet Mars, two identical spacecraft, each consisting of an orbiter and a lander, will be launched in the third quarter of 1975. Upon arrival at the planet, the Viking lander will separate from the Viking orbiter and descend to a soft landing at a selected site on the Mars surface. It was decided to perform a sine vibration test on the Viking spacecraft, in its launch configuration, to qualify it for the booster-induced transient-dynamic environment. It is shown that component-level testing is a cost- and schedule-effective prerequisite to the system-level, sine-vibration test sequences.

Barrett, S.↗

The extended mission of Viking

The extended mission of the Viking project emphasizing the study of weather on Mars is presented. Samples were acquired for the analysis of surface material, and investigations were made of the physical and magnetic properties of the surface, with orbiters and landers producing large quantities of photographs of the surface and of atmospheric phenomena. The operation and chronology of Viking Orbiter 1 and 2 and Viking Lander 1, including the Viking continuation, the survey, and the orbiter completion missions are discussed.

Snyder, C. W.↗

Strain gaged struts and data reduction techniques to maximize quality data from spacecraft flight measurements

The flight instrumentation for the Viking project was established to obtain environmental data, and maximize the data obtainable from the limited number of telemetry channels. To achieve these objectives, a set of six struts were strain gaged and calibrated as load cells to obtain a complete force-time history across an interface. The force-time history can be used with an analytical model to calculate the response of any part of the structure above the instrumented interface. Special matched filters were required to reduce the flight data and derive the phase correlated loads. Flight data results from the Viking Dynamic Simulator flown in February 1974 are described in addition to ground test results used to verify the data reduction process.

Day, F. D., III↗

The Viking missions to Mars.

The Viking Project will launch two unmanned spacecraft to Mars in 1975 for scientific exploration with special emphasis on the search for life. Each spacecraft will consist of an orbiter and a lander. The landing site will be selected after the spacecraft is in orbit. Twelve investigations will be performed: three mapping experiments from the orbiter, one atmospheric experiment during the lander entry phase, seven analytical experiments on the surface of the planet, and one using the spacecraft radio and radar systems. The experiments on the surface will deal principally with biology, geology, and meteorology. Sixty-three scientists have been selected for the twelve teams.

Soffen, G. A.↗

Entry science experiments for Viking 1975.

A review is given of our present knowledge of the Martian atmosphere with special emphasis on the results obtained by the Mariner 4, 6 and 7 fly-bys. The Viking Project offers the first opportunity for in situ measurements which should resolve many questions left open by previous work. A description is given of the neutral gas mass spectrometer and retarding potential analyzer experiments to be performed as the lander enters the upper atmosphere and the experiments planned for determining atmospheric structure as the lander approaches the surface of the planet.

Nier, A. O.↗

Mariner 9 and the exploration of Mars.

Review of the progress of Mariner series spacecraft with details on the Mariner 4, 6, 7, 8, and 9 missions and equipment. The systems of Mariner 9 are discussed in great detail. Mariner 9 photographs of Mars, Phobos, Diemos, Martian peaks, Nix Olympica, Martian equatorial region, and some other Martian surface details are included. Diagrams of Mariner 9 daily operating profile, of Mariner 9 TV coverage vs time in orbit, and of Mariner 9 in superior conjunction on Sept. 7, 1972 are also given. It is hoped that Martian landing missions as planned in 1975 by the Viking project will be more productive than Mariner 9 in answering the question of whether life did, or does, exist on that planet.

Parks, R. J.↗

Development of the propulsion subsystem for the Viking 75 Orbiter

The development of the Viking 75 Orbiter propulsion subsystem has been completed and qualification is under way. This development required an extension of the Mariner Mars 1971 propulsion subsystem technology to meet the Viking 75 requirements of three times the burn time and five times the number of burns. Modifications have been incorporated into the rocket engine to increase the cooling margin for the 2700-second Mars orbit insertion burn. This capability has been demonstrated in both engine firings and subsystem tests. A new surface tension device has been developed to position the propellants (N2O4 and MMH) over the tank outlets during zero-g flight. Extensive scale model testing has been conducted to prove this propellant management concept. This subsystem will provide midcourse corrections, an orbit insertion burn and 20 orbit trims for the Viking 75 Spacecraft. The Viking Project is managed by the Langley Research Center, National Aeronautics and Space Administration.

Vote, F. C.↗

Interactive design of large end rings on stiffened conical shells using composites

Design study methods and results for a composite reinforced base ring for the conical aeroshell structure of the planetary lander vehicle for Project Viking, an unmanned mission to Mars, are presented. The aeroshell is a ring and stringer-stiffened conical shell structure having a half angle of 70 degrees with a large base ring mounted at the outer edge of the cone and a large pay-load ring in the interior with many smaller rings spaced along the inside shell surface. The purpose of the structure is to develop the aerodynamic drag required to decelerate the lander in the Mars atmosphere to facilitiate a soft landing. The design of a shell structure of this complexity requires the use of the latest technology available in a large general-purpose shell buckling program. The large general-purpose non-linear shell buckling program (BOSOR 2) which was used for this purpose is described.

Davis, R. C.↗

Design of a Mars entry 'aeroshell'

The external shell of the Project Viking capsule, which will provide atmospheric deceleration for the 1976 landing of an unmanned spacecraft on the surface of Mars, is a wide-angle, stiffened cone subject to buckling under entry aerodynamic pressure. Complex, highly optimized structural prototype and flight designs were evolved through the application of relatively advanced buckling analysis methodology. Both designs were evaluated through tests and analysis with improved shell-of-revolution computer programs. Deviations between the analyses and experiments were resolved only by modeling the thin-walled rings as shell branches. The results illustrate the great complexity of shell behavior and the designer's need for reliable analysis tools capable of representing detailed structural behavior with greater accuracy than is current practice.

Leonard, R. W.↗

The Vikings are coming

The exploration of Mars with the aid of the two Viking landers is discussed. The probable landing date for Viking Lander 1 will be July 4, 1976, and for Lander 2 September 4, 1976. The criteria used in selecting the landing site are considered along with the procedure to be employed in the final approach of the lander to the planet and the touchdown. A description is given of the studies to be conducted by the lander, taking into account the search for life and the collection of meteorological and seismological data. Attention is also given to technical data concerning the spacecraft, details regarding the software, and the ground facilities on earth which are used for the Viking project.

Spitzer, C. R.↗

Viking balloon launched decelerator tests

The Viking Project utilized a 16.2M diameter disk-gap-band parachute to successfully land two research spacecraft on the surface of Mars during the summer of 1976. Unique specifications were imposed upon both the decelerator system and the balloon systems which were employed to provide a high altitude launch platform for a rocket powered test vehicle. The performance and stability of the balloon system and the predictability of the test vehicle trajectory offered interesting challenges. Descriptions of the development work for suitable materials, fabrication techniques and peculiarities, and testing requirements for both the decelerator and balloon systems will be presented.

Timmons, J. D.↗

The Viking Orbiter cameras' potential for photometric measurement

Although photometry of Mars is not listed as a major mission objective, the Viking Project has provided the Orbiter Imaging Team with cameras exhibiting significant improvement in photometric measurement as compared with past Mariners. Sample calibration data are described, together with predicted performance capabilities.

Thorpe, T. E.↗